Two-dimensional bar code symbol capture devices are known in the art. An example of such device is shown in U.S. Patent Publication No. 2003/0089776, a figure from which is reproduced as FIG. 1 here.
These image capture devices typically include a CMOS or other type of light sensor that comprises an array of sensing elements, each of which outputs an electrical signal proportional or in some way related to the amount of incident light. The image may then be stored electronically for later processing or reproduction.
Such image capture devices typically include the sensor mounted on a printed circuit board (PCB) and placed behind a set of one or more lenses, as shown in the '776 publication cited above, and in FIG. 1 hereof. Additionally, the prior art image capture devices often include an illumination means, a set of several light sources to light up the symbol being imaged, and to help aim the image capture device at the symbol to be captured.
The aiming light is used to help ascertain where to position the image capture device. By positioning the aiming light, often implemented as a series of LEDS, in the correct place, a user can ascertain when the image capture device is correctly positioned to be activated for capturing the desired image.
Several problems exist with these prior art devices. First, any lenses associated with the illumination LEDs must be correctly adjusted to properly illuminate the symbol or image to be captured. Specifically, the distance between the lens and the illumination and aiming LEDs must be correctly set.
However, the additional lens or lenses employed to direct light reflected from the image onto the sensor must also be adjusted, so that the distance between these additional lenses and the sensor are also correct. Because these two adjustments are related in a rather complicated and nonlinear fashion, it is very difficult to properly adjust focal lengths in an arrangement such as that shown in the '776 publication.
Another problem in such systems results from the type of sensor array utilized. More specifically, these types of sensor arrays may be packaged in several different types of packages, such as bare chip mount, ceramic packaging, or what has commonly become known as BGA or ball grid array packaging. Ball grid array packaging is a type of shell case packaging known in the art and which permits the size of the package to be minimized.
In the conventional image capture devices, BGA type of packaging is rarely if ever employed. One of the problems with BGA type packaging is that when mounted on a PCB for use in the camera module, stray light from the opposite side of the PCB reaches the BGA packaged sensor array, and causes distortion of the image. However, BGA type of packaging is beneficial for making the camera module as small as possible. Therefore, there are competing requirements when this type of packaging is employed.
In view of the foregoing, there exists a need in the art for a more efficient image capture device utilizing BGA type sensors.